Underreamer



fPA'rENT OFFICE.

CHARLES L. DUNHAM, 0F PENNSBORO, WEST VIRGHIAn 'UN'DERREAMER.

Specification of Letters Patent.

Patented Aug. 10, 1920.

Application mea May 15, 1920. serial N. 381,721.

To all whom t may concer/n.:

Be it known that I, CHARLES L. DUNHAM, a citizen of the United States, residing at Pennsboro, in the county of Ritchie and State of WestVirginia, have invented certain new and useful Improvements in Underreamers, of which the following is a specification.

This invention relates to underreamers and the object thereof is' to provide a device of thecharacter stated, in a manner as hereinafter set forth, for enlarging the bore of a well at any desired point thereof, but it is to be understood that the device may be used for any purpose wherein it is found applicable.

Further objects of the invention are to provide a device of the type specified which is simple in its construction and arrangement, stron durable and efficient in its use, formed of ew parts, readily assembled, and comparatively inexpensive to manufacture.

To the accomplishment of these and such other objects as may hereinafter appear, the invention consists of the novel construction, combination and arrangement of parts herein specically described and illustrated in the accompanying drawing wherein is shown an embodiment ofthe invention, but it is to be understood that changes, variations and modifications may be resorted to which come within the scope of the claims hereunto appended.

In the drawing forming a portion of this specification and wherein like numerals of Areference designate corresponding parts throughout the several views:

Figure 1 is an elevation of an underreamer in accordance with this invention.

Fig. 2 is an elevation of an underreamer, partly in section, extended into a casing also in section.

the transverse slot 2. A pair of opposed.

cutters 3, each provided with a shank 4, at its upper end, extending into the slot 2, are piyotally connected by means of the pins 5, which extend through the body portion 1 and through respective Shanks of the cutters 3 in the slot 2.

A pair of opposed and longitudinally extending dovetailed slideways 6 are formed on the periphery of the body portion l at the lower end thereof. The slideways 6 taper inwardly toward each other at their lower ends, that is, each of the said slideways is of greater depth at its lower end than at its upper end. An actuating member 7, having a dovetailed portion 8, is slidably mounted for vertical movement in each of the slideways 6.

l Atransversely extending rod 9 is lloosely carried by the lower ends of the actuating members 7 to which a pair of spreaders 10 are pivotally connected. Another transversely extending rod 11 is loosely carried by the lower ends of the actuating members 7 which is positioned above the rod 9 and to which the lower end of the spring 12 is connected. The upper end of the spring 12 is attached to the rod 13 extending .transversely across the slot 2. The action of the spring 12 is such as to normally hold the actuating members 7 in the extreme upward position in the slideways 6.

- Fach of the spreaders 10 has an enlarged rounded outer end 14 which engages in the respective pocket or slot l'formed therefor in the facing sides of the opposed cutters 3, as clearly Shown in Fi 2 of the drawing.

The actuating mem ers 7 are each provided with a projecting portion 16 which extends outwardly from its respective slideway 6 and has an inclined upper end 17.

The action of the spring 12 will normally hold the cutters 3 extended by extending the spreaders l0, but when the under-reamer is moved upwardly through the caslng 18, the latter will force the actuating members 7 downwardly by its engagement with the projecting portions 16 thereof. Owing to the greater depth of the slideways 6 at thelr lower ends, the downward movement o f the actuating members therein will permit lts passage through the casing 18 and cause the contraction of the cutters 3 also permitting their passage through the casing.

The construction of the cutters 3 1s such as to provide a clearance 19 between their lower ends and the inner wall of the casing 18 when the said cutters 3 are contracted to facilitate the downward passage of the reamer through the casing 18.

When the cutters 3 are extended the shoulders 20 thereof abut against the lower end 2l of the body portion 1 thereby carry ing the strain of the reaming operation which otherwise would be borne by the pins 5 which connect the cutters 3 with the body portion.

What I claim is:

1. A reamer comprising a body portion having its lower end bifurcated and further provided with peripheral s'lideways, cutters having Shanks extended into the furcation of and pivotally connected to the body p0rtion, spreaders engaging the cutters, and spring controlled actuating means for the spreaders shiftable in the slideways.

2. A reamer comprising a body portion having its lower end bifurcated and further provided with peripheral slideways, cutters having Shanks extended into the furcation of and pivotally connected to the body portion, spreaders engaging the cutters, and spring controlled actuating means for the spreaders shiftable in the slideways, said spreaders pivotally connected with said actuating means.

3. A reamer comprising a body portion having its lower end bifurcated and further provided with peripheral slideways, cutters having Shanks extended into the furcation of and pivotally connected to the body portion, spreaders engaging the cutters, and spring controlled actuating means for the spreaders shiftable in the slideways, said actuating means includingactuating members having said spreaders pivotally connected therewith.

4. A reamer comprising a body portio having itsl lower end bifurcated and further provided with peripheral slideways, cutters having Shanks extended into the furcation of and pivotally connected to the body portion, spreaders engaging the cutters, and spring controlled actuating means for the spreaders shiftable in the slideways, said cutters having slots for the reception of the spreaders and said spreaders having enlarged outer ends.

5. A reamer comprising a body portion, a pair of cutters pivotally connected therewith, .spreaders engaging the cutters to maintain them extended, and a spring conv trolled actuating means for the spreaders, said actuating means slidably mounted on the periphery of the body portion and having l'lsaid spreaders pivotally connected therewit In testimony whereof 'I ax my si ature.

CHARLES L. DU 

